The present invention provides 4-oxo4,7-dihydro-thieno[2,3-b]pyridine-5-carboxamide derivatives, more specifically, 5-benzylaminocarbonyl4-oxo-4,7-dihydro-thieno[2,3-b]pyridine derivatives of formula (I), which are useful as antiviral agents (e.g. as agents against viruses of the herpes family).
The herpesviruses comprise a large family of double stranded DNA viruses. They are also a source of the most common viral illnesses in man. Eight of the aherpes viruses, herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella zoster virus (VZV), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), and human herpes viruses 6, 7, and 8 (HHV-6, HHV-7, and HHV-8), have been shown to infect humans.
HSV-1 and HSV-2 cause herpetic lesions on the lips and genitals, respectively. They also occasionally cause infections of the eye and encephalitis. HCMV causes birth defects in infants and a variety of diseases in immunocompromised patients such as retinitis, pneumonia, and gastrointestinal disease. VZV is the causative agent of chicken pox and shingles. EBV causes infectious mononucleosis. It can also cause lymphomas in immunocompromised patients and has been associated with Burkitt""s lymphoma, nasopharyngeal carcinoma, and Hodgkins disease. HHV-6 is the causative agent of roseola and may be associated with multiple sclerosis and chronic fatigue syndrome. HHV-7 disease association is unclear, but it may be involved in some cases of roseola. HHV-8 has been associated with Kaposi""s sarcoma, body cavity based lymphomas, and multiple myeloma.
Applicant has discovered compounds that are useful as antiviral agents for treating herpesviral infections. Accordingly, the invention provides a compound of 
or a pharmaceutically acceptable salt thereof wherein,
R1 is
(a) Cl,
(b) Br,
(c) CN,
(d) NO2, or
(e) F;
R2 is
(a) H,
(b) R5,
(c) NR7R8,
(d) SO2R9, or
(e) OR9;
R3 is
(a) H,
(b) halo,
(c) aryl,
(d) S(O)mR6,
(e) (Cxe2x95x90O)R6,
(f) (Cxe2x95x90O)OR9,
(g) cyano,
(h) het, wherein said het is bound via a carbon atom,
(i) OR10,
(j) Ohet,
(k) NR7R8 
(l) SR10,
(m) Shet,
(n) NHCOR12,
(o) NHSO2R12, or
(p) C1-7alkyl which may be partially unsaturated and optionally substituted by one or more substituents of the group R11, OR13, SR10, SR13, NR7R8, halo, (Cxe2x95x90O)C1-7alkyl, and SOmR9;
R4 is
(a) H,
(b) halo,
(c) C1-4alkyl, or
(d) R4 together with R3 form a carbocyclic or het, either of which may be optionally substituted by NR7R8, by C1-7alkyl which may be optionally substituted by OR14, or by het, wherein said het is bound via a carbon atom;
R5 is
(a) (CH2CH2O)iR10,
(b) het, wherein said het is bound via a carbon atom,
(c) aryl,
(d) C1-7alkyl which may be partially unsaturated and is optionally substituted by one or more substituents selected from a group consisting of NR7R8, R11, SOmR9, and OC2-4alkyl which may be further substituted by het, OR10, or NR7R8, or
(e) C3-8cycloalkyl which may be partially unsaturated and optionally substituted by one or more substituents selected from a group consisting of R11, NR7R8, SOmR9, and C1-7alkyl optionally substituted by R11, NR7R8, or SOmR9;
R6 is
(a) C1-7alkyl,
(b) NR7R8,
(c) aryl, or
(d) het, wherein said het is bound via a carbon atom;
R7 and R8 are independently
(a) H,
(b) aryl,
(c) C1-7alkyl which may be partially unsaturated and is optionally substituted by one or more substituents selected from a group consisting of NR10R10, R11, SOmR9, CONR10R10, and halo, or,
(d) R7 and R8 together with the nitrogen to which they are attached form a het;
R9 is
(a) aryl,
(b) het,
(c) C3-8cycloalkyl, or
(d) C1-7alkyl which may be partially unsaturated and is optionally substituted by one or more substituents selected from a group consisting of NR10R10, R11, SH, CONR10R10, and halo;
R10 is
(a) H, or
(b) C1-7alkyl optionally substituted by OH;
R11 is
(a) OR10,
(b) Ohet,
(c) Oaryl,
(d) CO2R10,
(e) het,
(f) aryl, or
(g) CN;
R12 is
(a) H,
(b) het,
(c) aryl,
(d) C3-8cycloalkyl, or
(e) C1-7alkyl optionally substituted by NR7R8 or R11;
R13 is
(a) (Pxe2x95x90O)(OR14)2,
(b) CO(CH2)nCON(CH3)xe2x80x94(CH2)nSO3xe2x88x92M+,
(c) an amino acid,
(d) C(xe2x95x90O)aryl, or
(e) C(xe2x95x90O)C1-7alkyl optionally substituted by NR7R8, aryl, het, CO2H, or O(CH2)nCO2R14);
R14 is
(a) H, or
(b) C1-7alkyl;
each i is independently 2, 3, or 4;
each n is independently 1, 2, 3, 4 or 5;
each m is independently 0, 1, or 2;
M is sodium, potassium, or lithium;
wherein any aryl is optionally substituted with one or more substituents selected from the group consisting of halo, OH, cyano, CO2R14, CF3, C1-6alkoxy, and C1-6alkyl which maybe further substituted by one to three SR14, NR14R14, OR14, het, or CO2R14; and
wherein any het is optionally substituted with one or more substituents selected from the group consisting of halo, OH, cyano, phenyl, CO2R14, CF3, C1-6alkoxy, oxo, oxime, and C1-6alkyl which maybe further substituted by one to three SR14, NR14R14, OR14, or CO2R14.
In another aspect, the present invention also provides:
a pharmaceutical composition comprising a compound of formula I, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient (the composition preferably comprises an effective antiviral amount of the compound or salt);
a method of treating or preventing a herpesviral infection, comprising administering to a mammal (e.g. a human) in need of such treatment, a compound of formula (I) or a pharmaceutically acceptable salt thereof; and
a method for inhibiting a viral DNA polymerase, comprising contacting (in vitro or in vivo) the polymerase with an effective inhibitory amount of a compound of formula I, or a pharmaceutically acceptable salt thereof.
The invention also provides novel intermediates and processes disclosed herein that are useful for preparing compounds of formula L.
Compounds of formula I have a 4-substituted benzylaminocarbonyl substituent at the 5-position of the thieno[2,3-b]pyridine ring system. This substitution pattern has been found to provide compounds with significantly improved antiviral activity compared to thienopyridines lacking this substitution.
The following definitions are used, unless otherwise described: halo is fluoro, chloro, bromo, or iodo. Alkyl, alkoxy, etc. denote both straight and branched groups; but reference to an individual radical such as xe2x80x9cpropylxe2x80x9d embraces only the straight chain radical, a branched chain isomer such as xe2x80x9cisopropylxe2x80x9d being specifically referred to. When alkyl can be partially unsaturated, the alkyl chain may comprise one or more (e.g. 1, 2, 3, or 4) double or triple bonds in the chain.
Aryl denotes a phenyl radical or an ortho-fused bicyclic carbocyclic radical having about nine to ten ring atoms in which at least one ring is aromatic. Het is a four- (4), five- (5), six- (6), or seven- (7) membered saturated or unsaturated heterocyclic ring having 1, 2, 3, or 4 heteroatoms selected from the group consisting of oxy, thio, sulfinyl, sulfonyl, and nitrogen, which is optionally fused to a benzene ring, or any bicyclic heterocycle group. Het includes xe2x80x9cheteroaryl,xe2x80x9d which encompasses a radical attached via a ring carbon of a monocyclic aromatic ring containing five or six ring atoms consisting of carbon and 1, 2, 3, or 4 heteroatoms each selected from the group consisting of non-peroxide oxy, thio, and N(X) wherein X is absent or is H, O, C1-4alkyl, phenyl or benzyl, as well as a radical of an ortho-fused bicyclic heterocycle of about eight to ten ring atoms derived therefrom, particularly a benz-derivative or one derived by fusing a propylene, trimethylene, or tetramethylene diradical thereto.
When R4 together with R3 form a carbocyclic, R4 and R3 together can be a 3, 4, 5, or 6 membered saturated or unsaturated carbon chain.
xe2x80x9cAmino acid,xe2x80x9d includes a residue of natural amino acid (e.g. Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Hyl, Hyp, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, and Val) in D or L form, as well as unnatural amino acids (e.g. phosphoserine, phosphothreonine, phosphotyrosine, hydroxyproline, gamma-carboxyglutamate; hippuric acid, octahydroindole-2-carboxylic acid, statine, 1,2,3,4,-tetrahydroisoquinoline-3-carboxylic acid, penicillamine, ornithine, citruline, a-methyl-alanine, para-benzoylphenylalanine, phenylglycine, propargylglycine, sarcosine, and tert-butylglycine). An amino acid can conveniently be linked to the remainder of a compound of formula I through the carboxy terminus, the amino terminus, or through any other convenient point of attachment, such as, for example, through the sulfur of cysteine. In particular, an amino acid can conveniently be linked to the remainder of a compound of formula I through the carboxy terminus.
It will be appreciated by those skilled in the art that compounds of the invention having a chiral center may exist in and be isolated in optically active and racemic forms. Some compounds may exhibit polymorphism. It is to be understood that the present invention encompasses any racemic, optically-active, polymorphic, tautomeric, or stereoisomeric form, or mixture thereof, of a compound of the invention, which possesses the useful properties described herein, it being well known in the art how to prepare optically active forms (for example, by resolution of the racemic form by recrystallization techniques, by synthesis from optically-active starting materials, by chiral synthesis, or by chromatographic separation using a chiral stationary phase) and how to determine antiviral activity using the standard tests described herein, or using other similar tests which are well known in the art. In particular, it is understood that compounds of formula I wherein R2 is hydrogen can exist in the corresponding tautomeric xe2x80x9cenolxe2x80x9d form, and that such tautomers are included as compounds of the invention.
The carbon atom content of various hydrocarbon-containing moieties is indicated by a prefix designating a lower and upper number of carbon atoms in the moiety, i.e., the prefix Ci-j indicates a moiety of the integer xe2x80x9cixe2x80x9d to the integer xe2x80x9cjxe2x80x9d carbon atoms, inclusive. Thus, for example, C1-7alkyl refers to alkyl of one to seven carbon atoms, inclusive.
The compounds of the present invention are generally named according to the IUPAC or CAS nomenclature system. Abbreviations which are well known to one of ordinary skill in the art may be used (e.g. xe2x80x9cPhxe2x80x9d for phenyl, xe2x80x9cMexe2x80x9d for methyl, xe2x80x9cEtxe2x80x9d for ethyl, xe2x80x9chxe2x80x9d for hour or hours and xe2x80x9crtxe2x80x9d for room temperature).
Specific and preferred values listed below for radicals, substituents, and ranges, are for illustration only; they do not exclude other defined values or other values within defined ranges for the radicals and substituents. The compounds of the invention include compounds of formula I having any combination of the values, specific values, more specific values, and preferred values described herein.
Specifically, C1-7alkyl can be methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl, pentyl, 3-pentyl, hexyl, or heptyl; C3-8cycloalkyl can be cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, or cyclooctyl; C1-7alkoxy can be methoxy, ethoxy, propoxy, isopropoxy, butoxy, iso-butoxy, sec-butoxy, pentoxy, 3-pentoxy, hexyloxy, 1-methylhexyloxy, or heptyloxy; C(xe2x95x90O)C1-7alkyl can be acetyl, propanoyl, butanoyl, pentanoyl, 4-methylpentanoyl, hexanoyl, or heptanoyl; aryl can be phenyl, indenyl, or naphthyl; het can be pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl, or heteroaryl; and heteroaryl can be furyl, imidazolyl, triazolyl, triazinyl, oxazoyl, isoxazoyl, thiazolyl, isothiazoyl, pyrazolyl, pyrrolyl, pyrazinyl, tetrazolyl, pyridyl, (or its N-oxide), thienyl, pyrimidinyl (or its N-oxide), indolyl, isoquinolyl (or its N-oxide) or quinolyl (or its N-oxide).
When C1-7alkyl is partially unsaturated, it can specifically be vinyl, allyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butadienyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 5-hexene-1-ynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, or 5-hexynyl.
A specific value for Het is a five- (5), six- (6), or seven- (7) membered saturated or unsaturated ring containing 1, 2, 3, or 4 heteroatoms selected from the group consisting of non-peroxide oxy, thio, sulfinyl, sulfonyl, and nitrogen; as well as a radical of an ortho-fused bicyclic heterocycle of about eight to twelve ring atoms derived therefrom, particularly a benz-derivative or one derived by fusing a propylene, trimethylene, tetramethylene or another monocyclic het diradical thereto.
A specific value for R1 is F, Cl, or Br.
A more specific value for R1 is Cl.
A specific value for R2 is H.
A specific value for R2 is R5, NR7R8, SO2R9, or OR9.
A specific value for R2 is R5.
A more specific value for R2 is methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, carboxymethyl, (C1-7 alkoxy)carbonylmethyl, 2-hydroxyethyl, 2-(2-methoxy-ethoxy)ethyl, 3-(2-tetrahydropyranyloxy)propyl, 2-morpholinoethyl, 2-(diethylamino)ethyl, 2-(dimethylamino)ethyl, 2-piperidinoethyl, 3-piperidinopropyl, 2-(1-methylpyrrolidin-2-yl)ethyl, 2-(diisopropylamino)ethyl, 2-pyrrolidin-1-ylethyl, 3-(dimethylamino)propyl, benzyl, 3-fluorobenzyl, 3-phenylpropyl, 2-tetrahydrofuranylmethyl, 2-pyrrolidinoethyl, 3-pyridylmethyl, or vinyl.
A more specific value for R2 is methyl, ethyl, isopropyl, 2-hydroxyethyl, 2-(diethylamino)ethyl, or 2-(dimethylamino)ethyl.
A specific value for R3 is H, halo, S(O)mR6, (Cxe2x95x90O)R6, (Cxe2x95x90O)OR9, cyano, or C1-7alkyl which may be partially unsaturated and optionally substituted by one or more substituents of the group R11, OR13 SR10, SR13, NR7R8, halo, (Cxe2x95x90O)C1-7alkyl, and SOmR9.
A specific value for R3 is C1-7alkyl which may be partially unsaturated and optionally substituted by one or more substituents of the group R11, OR13, SR10, SR13, NR7R8, halo, (Cxe2x95x90O)C1-7 alkyl, and SOmR9.
A specific value for R3 is C1-7alkyl which may be partially unsaturated and is substituted by one or more substituents of the group R11, OR13, SR10, SR13, NR7R8, halo, (Cxe2x95x90O)C1-7alkyl, and SOmR9.
A specific value for R3 is C1-7alkyl which may be partially unsaturated and is substituted by one or more substituents of the group OR10, het and NR7R8.
A specific value for R3 is (Z or E)xe2x80x94CHxe2x95x90CH(CH2)nRa or xe2x80x94Cxe2x89xa1C(CH2)nRa wherein Ra is R11, OR13, SR10, SR13, NR7R8, halo, (Cxe2x95x90O)C1-7alkyl, or SOmR9.
A more specific value for R3 is bromo, iodo, 3-hydroxy-1-propynyl, 3-methoxy-1-propynyl, 4-hydroxy-1-butynyl, 3-hydroxypropyl, cyano, 4,4-di(methoxycarbonyl)-1-butynyl, 4-hydroxybutyl, 3-(3-carboxypropanoyloxy)-1-propynyl, 3-(morpholinoacetoxy)-1-propynyl, 3-(2-amino-3-methylbutanoyloxy)-1-propynyl, thiomorpholinomethyl, N-[2-(4-hydroxyphenyl)-2-hydroxyethyl]-N-(methyl)aminomethyl, morpholinocarbonyl, or 3-[3-(morpholinomethyl)benzoyloxy]-1-propynyl.
A more specific value for R3 is iodo, 3-hydroxy-1-propynyl, 4-hydroxy-1-butynyl, 3-hydroxypropyl, morpholinomethyl, N-[2-(4-hydroxyphenyl)-2-hydroxyethyl]-N-(methyl)aminomethyl or 4-hydroxybutyl.
A specific value for R3 is 3-hydroxy-1-propynyl, morpholinomethyl, N-[2-(4-hydroxyphenyl)-2-hydroxyethyl]-N-(methyl)aminomethyl or 3-hydroxypropyl.
A specific value for R5 is (CH2CH2O)iR10.
A specific value for R5 is C1-7alkyl which may be partially unsaturated and is optionally substituted by one or more substituents selected from a group consisting of NR7R8, R11, SOmR9, and OC2-4alkyl, which may be further substituted by het, OR10, or NR7R8; wherein R9 and R10 have any of the values defined herein; and
wherein R7 and R8 are independently
(a) H,
(b) aryl, or
(c) C1-7alkyl which may be partially unsaturated and is optionally substituted by one or more substituents selected from a group consisting of NR10R10, R11, SOmR9, CONR10R10, or halo; and,
R11 is
(a) OR10,
(b) Ohet,
(c) Oaryl,
(d) CO2R10, or
(e) CN.
A specific value for R5 is C1-7alkyl which may be partially unsaturated and is optionally substituted by one or more substituents selected from a group consisting of NR7R8, R11, SOmR9, and OC2-4alkyl, which may be further substituted by het, OR10, or NR7R8.
A specific value for R5 is C1-7alkyl, which may be partially unsaturated and is optionally substituted by one or more aryl or het.
A more specific value for R5 is C1-7alkyl.
A specific compound of formula I is a compound wherein any aryl, or het is optionally substituted with one or two substituents selected from the group consisting of halo, cyano, het, trifluoromethyl, trifluoromethoxy, hydroxy C1-7alkoxy, and C1-7alkyl; or a pharmaceutically acceptable salt thereof.
Preferred compounds of formula I exclude compounds disclosed specifically or generically in the references cited herein. A preferred compound of formula I excludes a compound of formula I wherein R1 is halo when R2 is hydrogen. Such excluded compounds of formula I can be included in the pharmaceutical compositions and methods described herein or can be excluded therefrom.
The following Charts A-L describe the preparation of the compounds of the present invention. All of the starting materials are prepared by procedures described in these charts or by procedures analogous thereto, which would be well known to one of ordinary skill in organic chemistry. All of the final compounds of the present invention are prepared by procedures described in these charts, by procedures analogous thereto, or by procedures which are known to one of ordinary skill in organic chemistry. All of the variables used in the charts are as defined below or as in the claims.
Chart A.
Optionally substituted 2-aminothiophenes of the formula A-1 are prepared via reduction of the corresponding nitro compounds A-2. Compounds of the formula A-1 are then heated with diethylethoxymethylene malonate followed by thermolysis in diphenyl ether to yield esters of the formula A-4. The esters are converted to amides of the formula A-6 via direct aminolysis with an optionally substituted benzylamine at 190xc2x0 C. or via hydrolysis to acids of the formula A-5 followed by treatment with carbonyldiimidazole and the amine. Compounds of the formula A-6 are treated with an optionally substituted alkyl halide in the presence of potassium carbonate to yield N-alkylated amides of the formula A-7. 
Chart B.
Compound B-1 (5-nitro-2-thiophenesulfonyl chloride) is treated with an amine to yield nitro compounds of the formula B-2. Compounds of the formula B-2 are transformed as in Chart A to yield amides analogous to A-6 and A-7. 
Chart C.
Compounds of the formula C-1 where R is H or alkyl are halogenated to yield compounds of the formula C-2. Compounds of the formula C-2 are transformed as in Chart A to yield amides analogous to A-6 and A-7. 
Chart D.
Palladium and copper mediated coupling of D-1 (where X=Br or I) with an alkyne leads to compounds of the formula D-2. Compounds of the formula D-2 are hydrogenated using palladium on carbon as the catalyst to yield the saturated compounds D-4. Compounds D-2 and D-4 are treated with an optionally substituted alkyl halide to yield N-alkylated compounds D-3 and D-5. 
Chart E.
Compound E-1 is treated with copper (I) cyanide to yield the cyano compound E-2. 
Chart F.
Compounds of the formula F-1 are treated with an optionally substituted alkyl halide in the presence of potassium carbonate to yield N-alkylated esters of the formula F-2. The esters are converted to amides of the formula A-7 via direct aminolysis with a substituted benzylamine or via hydrolysis to acids of the formula F-3 followed by treatment with carbonyldiimidazole and the amine. 
Chart G.
Palladium and copper mediated coupling of G-1 (where R=Br or I) with an alkyne leads to compounds of the formula D-3. Compounds D-3 are hydrogenated using palladium on carbon as the catalyst to yield saturated compounds of the formula D-5. 
Chart H.
Compounds of the formula H-1 are treated with an acylating agent to yield compounds of the formula H-2 where A is either an alkyl or arylalkyl substituent and X is a halogen (Br, Cl, or I). The halide is then displaced by an amine to yield compounds of the formula H-3. 
Chart I.
Compounds of formula I-4 bearing 2-alkylamino substitution are prepared by palladium catalyzed carboxylation of 2-iodothienopyridine E-1 to afford the corresponding 2-methylester I-1. Reduction of I-1 with LiAlH4 affords 2-hydroxymethyl derivative I-2 which may then be treated with an optionally substituted alkyl halide in the presence of potassium carbonate to yield N-alkylpyridones of the formula I-3. Activation of the alcohol with methanesulfonyl chloride followed by displacement with a primary or secondary amine provides compounds of formula I-4. 
Chart J.
N-(4-Chlorobenzyl)-4-hydroxythieno[2,3-b]pyridine-5-carboxamide (A-6 where R=H) undergoes a Mannich reaction by heating with morpholine and formaldehyde in acetic acid/ethanol to afford 2-morpholinomethyl derivative J-1. Compound J-1 is then treated with an optionally substituted alkyl halide in the presence of potassium carbonate or with an optionally substituted alcohol under Mitsunobu conditions to yield thienopyridones of the general formula J-2. 
Chart K.
2-Iodothienopyridine-5-carboxamide E-1 undergoes palladium catalyzed carbon monoxide insertion with trapping by an amine to afford 2-carboxamides of the general formula K-1. Compounds K-1 are then treated with an optionally substituted alkyl halide in the presence of potassium carbonate to yield thiyridnes of the formula K-2. 
Chart L.
Aminomethylenemalonate L-2 is prepared as described in German patent 2447477 (1976) from tert-butyl 2-aminothiophene-3-carboxylate (L-1) (M. Gutschow and U. Neumann, J. Med. Chem. 1998, 41, 1729-1740) by reacting with diethyl ethoxymethylenemalonate. Intermediate L-2 is then alkylated at nitrogen by reaction with iodomethane in the presence of potassium carbonate affording L-3. Subsequently, L-3 undergoes a Mannich reaction with 4-methylene morpholinium chloride (Dimmock, JR, et al. Eur. J. Med. Chem. 1989, 24, 379-383) to provide the morpholinomethyl intermediate L4. Thieno[2,3-b]pyridone L-5 is then prepared by heating compound L4 in a mixture of Eaton""s reagent. Ester L-5 is then treated with a benzylamine (e.g. 4-chlorobenzylamine, 4-bromobenzylamine, or 4-fluorobenzylamine) at high temperature to afford the corresponding amides of the general formula L-7 or ester L-5 may be saponified to afford acid L-6 which is then coupled with a benzylamine to provide amides of the general formula L-7. 
Chart M
Compounds of the invention wherein R2 is (a) R5; (b) NR7R8; or (c) OR9 and R5 is (a) het, wherein said het is bound via carbon; (b) aryl; (c) C3-8cycloalkyl which may be partially unsaturated and optionally substituted by one or more substituents selected from a group consisting of R11, NR7R8, SOmR9, and C1-7alkyl optionally substituted by R11, NR7R8, or SOmR9; or (d) tert-butyl, are prepared as exemplified in Chart M. Intermediates bearing the 4-oxo4,7-dihydrothieno[2,3-b]pyridine ring system are prepared in a manner analogous to that precedent in the literature (M. M. El-Abedelah, M. Z. Nazer, S. F. Okasha, M. Calas, J. Bompart, P. Mion Eur. J. Med. Chem. 1998, 33, 33-42; and M. M. El-Abedelah, S. S. Sabri, A. A. Al-Ashqar Hetrocycles 1997, 45, 255-264). 2-Bromo-5-chloro-4-thiophenecarboxylic acid (M-1) (prepared as described by S. Ol, H. Nagaya, N. Inatomi, M. Nakao, H. Yukimasa WO-97/11705, 1997) is activated with 1,1xe2x80x2-carbonyldiimidazole and is then treated with ethyl trimethylsilyl malonate in the presence of DBU to afford 3-ketoester M-2. Refluxing compound M-2 in acetic anhydride and triethylorthoformate provides enol ether M-3. Compound M-3 is then contacted with a nitrogen containing compound of the formula RNH2 where R may be, but is not limited to, the R2 definition above (e.g., cyclopropylamine, tert-butylamine, aniline, 3-furylamine, 4-aminomorpholine, 1-amino-4-methylpiperazine, or O-ethylhydroxylamine) to afford a compound of formula M-4. The reaction can conveniently be carried out in ethanol. The resulting enamines M-4 are then cyclized by heating with sodium hydride (or other appropriate base) in tetrahydrofuran to afford the thieno[2,3-b]pyridine-5-carboxylic esters of formula M-5. The esters M-5 are heated in the presence of a substituted benzylamine (e.g., 4-chlorobenzylamine) and iodine to afford the corresponding carboxamides of the formula M-6. Alternatively, carboxamides of formula M-6 are prepared such that the esters M-5 are saponified in the presence of aqueous sodium hydroxide affording the corresponding carboxylic acid which is then coupled with a substituted benzylamine in the presence of 1,1xe2x80x2-carbonyldiimidazole. Compounds of the formula M-6 are transformed to derivatives in analogous fashion to that described in charts G and K. Specifically, compounds of formula M-6 are coupled with propargylic alcohol in the presence of Pd(PPh3)2Cl2, Cul, and diethylamine to afford compounds of the formula M-7. Saturation of the alkynyl functionality present in M-7 by hydrogenation over a palladium catalyst provides compounds of the formula M-8. 
Chart N
Alternatively, a subset of compounds bearing the R2 definition in Chart M where R3 is CH2NR7R8 are prepared as exemplified in Chart N. 3-Bromo-2-chlorothiophene (N-1) (prepared as described by J. J. Baldwin, J. M. Hoffman, J. H. Jones, C. S. Rooney, A. M. Smith U.S. Pat. No. 5,276,025; 1994) is metalated with lithium diisopropylamide in tetrahydrofuiran followed by quenching with N,N-dimethylformamide to afford carboxaldehyde N-2. Reductive amination of N-2 by treating with an amine (e.g., morpholine), acetic acid, and sodium triacetoxyborohydride affords thiophene N-3. Metalation of the compound N-3 with n-BuLi followed by trapping with carbon dioxide provides carboxylic acid N-4. Acid N-4 is activated with 1,1xe2x80x2-carbonyldiimidazole and is then treated with ethyl trimethylsilyl malonate in the presence of DBU to afford 3-ketoester N-5. Refluxing compound N-5 in acetic anhydride and triethylorthoformnate provides enol ether N-6. Compound N-6 is then contacted with a nitrogen containing compound of the formula RNH2 where R may be but is not limited to the R2 definition above (e.g., cyclopropylamine, tert-butylamine, aniline, 3-furylamine, 4-aminomorpholine, 1-amino4-methylpiperazine, or O-ethylhydroxylamine) to afford a compound of formula N-7. The reaction can conveniently be carried out in ethanol, The resulting enamines N-7 are then cyclized by heating with sodium hydride (or other appropriate base) in tetrahydrofuran to afford the thieno[2,3-b]pyridine-5-carboxylic esters of formula N-8. The esters N-8 are heated in the presence of a substituted benzylamine (e.g., 4-chlorobenzylamine) to afford the corresponding carboxamides of the formula N-9. Alternatively, carboxamides of formula N-9 are prepared such that the esters N-8 are saponified in the presence of aqueous sodium hydroxide in affording the corresponding carboxylic acid which is then coupled with a substituted benzylamine in the presence of 1,1xe2x80x2-carbonyldiimidazole. 
The invention also provides processes and intermediates described herein that are useful for preparing compounds of the invention. For example, the invention provides a method for preparing a compound of formula L-7: 
wherein R is C1-4alkyl; and X is Cl, Br, CN, NO2, or F, comprising steps 1-6 described below.
(1) Reacting an amine of formula L-1: 
with an alkoxymethylenemalonate of formula Rxe2x80x2OCHxe2x95x90CH(CO2W)2 wherein Rxe2x80x2 is C1-4alkyl and each W is independently selected from C1-4alkyl, to provide a compound of formula L-2: 
The reaction can conveniently be carried out by heating a solution of compound L-1 with the alkoxymethylenemalonate, or an equivalent thereof.
(2) Alkylating the compound of formula L-2 to provide a corresponding compound of formula L-3: 
wherein R is C1-4alkyl. The reaction can conveniently be carried out by contacting the compound of formula L-2 with an iodoalkane of formula I-R in the presence of a suitable base (e.g. an alkali metal carbonate).
(3) Reacting the compound of formula L-3 with a 4-methylenemorpholinium salt to provide a compound of formula L-4: 
The reaction can conveniently be carried out by contacting the ester with a suitable 4-methylenemorpholinium salt or with a combination of reagents that generates a 4-methylenemorpholinium salt in situ.
(4) Cyclizing the compound of formula L-4 under conditions suitable to provide a bicyclic ester of formula L-5: 
The cyclization can conveniently be carried out by contacting a compound of formula L-4 with a mixture of phosphorus pentoxide and methanesulfonic acid.
(5) Hydrolyzing the ester L-5 to provide a carboxylic acid of formula L-6: 
Suitable conditions for converting an ester to a corresponding carboxylic acid are well known in the art. The reaction can be carried out under any suitable conditions.
(6) Reacting the carboxylic acid formula L-6 with a 4-substituted benzyl amine to provide the compound of formula L-7. Suitable conditions for preparing an amide from a corresponding carboxylic acid are well known in the art. The reaction can be carried out under any suitable conditions. For example, the reaction can conveniently be carried out by activating the carboxylic acid with a suitable activating agent, and treating the resulting activated acid with the requisite 4-substituted benzyl amine to provide the compound of formula L-7.
The invention also provides a method for preparing a compound of formula (I) wherein R1-R4 have any of the values, specific values, or preferred values described herein, comprising reacting a corresponding carboxylic acid of formula (II): 
with a benzyl amine of the formula: 
wherein X is Cl, Br, CN, NO2, or F, under conditions suitable to provide the compound of formula (I). Suitable conditions for preparing an amide from a corresponding carboxylic acid are well known in the art. The reaction can be carried out under any suitable conditions. For example, the reaction can conveniently be carried out by activating the carboxylic acid with a suitable activating agent, and treating the activated acid with the requisite 4-substituted benzyl amine to provide the compound of formula (I). Suitable amines include 4-chlorobenzylamine, 4-fluorobenzylamine, 4-bromobenzylamine, 4-cyanobenzylamine, and 4-nitrobenzylamine.
In cases where compounds are sufficiently basic or acidic to form stable nontoxic acid or base salts, administration of the compounds as salts may be appropriate. Examples of pharmaceutically acceptable salts are organic acid addition salts formed with acids which form a physiological acceptable anion, for example, tosylate, methanesulfonate, acetate, citrate, malonate, tartarate, succinate, benzoate, ascorbate, xcex1-ketoglutarate, and xcex1-glycerophosphate. Suitable inorganic salts may also be formed, including hydrochloride, hydrobromide, sulfate, nitrate, bicarbonate, and carbonate salts.
Pharmaceutically acceptable salts may be obtained using standard procedures well known in the art, for example by reacting a sufficiently basic compound such as an amine with a suitable acid affording a physiologically acceptable anion. Alkali metal (for example, sodium, potassium or lithium) or alkaline earth metal (for example calcium) salts of carboxylic acids can also be made.
Compounds of the present invention can conveniently be administered in a pharmaceutical composition containing the compound in combination with a suitable excipient, the composition being useful in combating viral infections. Pharmaceutical compositions containing a compound appropriate for antiviral use are prepared by methods and contain excipients which are well known in the art. A generally recognized compendium of such methods and ingredients is Remington""s Pharmaceutical Sciences by E. W. Martin (Mark Publ. Co., 15th Ed., 1975). The compounds and compositions of the present invention can be administered parenterally (for example, by intravenous, intraperitoneal or intramuscular injection), topically, orally, or rectally, depending on whether the preparation is used to treat internal or external viral infections.
For oral therapeutic administration, the active compound may be combined with one or more excipients and used in the form of ingestible tablets, buccal tablets, troches, capsules, elixirs, suspensions, syrups, wafers, and the like. Such compositions and preparations should contain at least 0.1% of active compound. The percentage of the compositions and preparations may, of course, be varied and may conveniently be between about 2 to about 60% of the weight of a given unit dosage form. The amount of active compound in such therapeutically useful compositions is such that an effective dosage level will be obtained.
The tablets, troches, pills, capsules, and the like may also contain the following: binders such as gum tragacanth, acacia, corn starch or gelatin; excipients such as dicalcium phosphate; a disintegrating agent such as corn starch, potato starch, alginic acid and the like; a lubricant such as magnesium stearate; and a sweetening agent such as sucrose, fructose, lactose or aspartame or a flavoring agent such as peppermint, oil of wintergreen, or cherry flavoring may be added. When the unit dosage form is a capsule, it may contain, in addition to materials of the above type, a liquid carrier, such as a vegetable oil or a polyethylene glycol. Various other materials may be present as coatings or to otherwise modify the physical form of the solid unit dosage form. For instance, tablets, pills, or capsules may be coated with gelatin, wax, shellac or sugar and the like. A syrup or elixir may contain the active compound, sucrose or fructose as a sweetening agent, methyl and propylparabens as preservatives, a dye and flavoring such as cherry or orange flavor. Of course, any material used in preparing any unit dosage form should be pharmaceutically acceptable and substantially non-toxic in the amounts employed. In addition, the active compound may be incorporated into sustained-release preparations and devices.
The compounds or compositions can also be administered intravenously or intraperitoneally by infusion or injection. Solutions of the active compound or its salts can be prepared in water, optionally mixed with a nontoxic surfactant. Dispersions can also be prepared in glycerol, liquid polyethylene glycols, triacetin, and mixtures thereof and in oils. Under ordinary conditions of storage and use, these preparations contain a preservative to prevent the growth of microorganisms.
Pharmaceutical dosage forms suitable for injection or infusion can include sterile aqueous solutions or dispersions or sterile powders comprising the active ingredient which are adapted for the extemporaneous preparation of sterile injectable or infusible solutions or dispersions, optionally encapsulated in liposomes. In all cases, the ultimate dosage form should be sterile, fluid and stable under the conditions of manufacture and storage. The liquid carrier or vehicle can be a solvent or liquid dispersion medium comprising, for example, water, ethanol, a polyol (for example, glycerol, propylene glycol, liquid polyethylene glycols, and the like), vegetable oils, nontoxic glyceryl esters, and suitable mixtures thereof. The proper fluidity can be maintained, for example, by the formation of liposomes, by the maintenance of the required particle size in the case of dispersions or by the use of surfactants. The prevention of the action of microorganisms can be brought about by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars, buffers or sodium chloride. Prolonged absorption of the injectable compositions can be brought about by the use in the compositions of agents delaying absorption, for example, aluminum monostearate and gelatin.
Sterile injectable solutions can be prepared by incorporating the active compound in the required amount in the appropriate solvent with various of the other ingredients enumerated above, as required, followed by filter sterilization. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum drying and the freeze drying techniques, which yield a powder of the active ingredient plus any additional desired ingredient present in the previously sterile-filtered solutions.
For topical administration, the present compounds may be applied in pure form, i.e., when they are liquids. However, it will generally be desirable to administer them to the skin as compositions or formulations, in combination with a dermatologically acceptable carrier, which may be a solid or a liquid.
Useful solid carriers include finely divided solids such as talc, clay, microcrystalline cellulose, silica, alumina and the like. Useful liquid carriers include water, alcohols or glycols or water-alcohol/glycol blends, in which the present compounds can be dissolved or dispersed at effective levels, optionally with the aid of non-toxic surfactants. Adjuvants such as fragrances and additional antimicrobial agents can be added to optimize the properties for a given use. The resultant liquid compositions can be applied from absorbent pads, used to impregnate bandages and other dressings, or sprayed onto the affected area using pump-type or aerosol sprayers. Thickeners such as synthetic polymers, fatty acids, fatty acid salts and esters, fatty alcohols, modified celluloses or modified mineral materials can also be employed with liquid carriers to form spreadable pastes, gels, ointments, soaps, and the like, for application directly to the skin of the user.
Examples of useful dermatological compositions which can be used to deliver the compounds of formula I to the skin are known to the art; for example, see Jacquet et al. (U.S. Pat. No. 4,608,392), Geria (U.S. Pat. No. 4,992,478),. Smith et al. (U.S. Pat. No. 4,559,157) and Wortzman (U.S. Pat. No. 4,820,508).
Useful dosages of the compounds of formula I can be determined by comparing their in vitro activity, and in vivo activity in animal models. Methods for the extrapolation of effective dosages in mice, and other animals, to humans are known to the art; for example, see U.S. Pat. No. 4,938,949.
The compound is conveniently administered in unit dosage form; for example, containing 5 to 1000 mg, conveniently 10 to 750 mg, most conveniently, 50 to 500 mg of active ingredient per unit dosage form. The desired dose may conveniently be presented in a single dose or as divided doses administered at appropriate intervals, for example, as two, three, four or more sub-doses per day. The sub-dose itself may be further divided, e.g., into a number of discrete loosely spaced administrations; such as multiple inhalations from an insufflator or by application of a plurality of drops into the eye.
For internal infections, the compositions can be administered orally or parenterally at dose levels, calculated as the free base, of about 0.1 to 300 mg/kg, preferably 1.0 to 30 mg/kg of mammal body weight, and can be used in man in a unit dosage form, administered one to four times daily in the amount of 1 to 1000 mg per unit dose.
For parenteral administration or for administration as drops, as for eye infections, the compounds are presented in aqueous solution in a concentration of from about 0.1 to about 10%, more preferably about 0.1 to about 7%. The solution may contain other ingredients, such as emulsifiers, antioxidants or buffers.
Generally, the concentration of the compound(s) of formula I in a liquid composition, such as a lotion, will be from about 0.1-25 wt-%, preferably from about 0.5-10 wt-%. The concentration in a semi-solid or solid composition such as a gel or a powder will be about 0.1-5 wt-%, preferably about 0.5-2.5 wt-%.
The exact regimen for administration of the compounds and compositions disclosed herein will necessarily be dependent upon the needs of the individual subject being treated, the type of treatment and, of course, the judgment of the attending practitioner.
The antiviral activity of a compound of the invention can be determined using pharmacological models which are well known to the art, or using Test A described below.
The compounds of formula (I) and pharmaceutically acceptable salts thereof are useful as antiviral agents. Thus, they are useful to combat viral infections in animals, including man. The compounds are generally active against herpes viruses, and are particularly useful against the varicella zoster virus, the Epstein-Barr virus, the herpes simplex virus, the human herpes virus type 8 (HHV-8) and the cytomegalovirus (CMV).
While many of the compounds of the present invention have shown activity against the CMV polymerase, these compounds may be active against the cytomegalovirus by this or other mechanisms of action. Thus, the description below of these compounds"" activity against the CMV polymerase is not meant to limit the present invention to a specific mechanism of action.
Test A.
The HCMV polymerase assay is performed using a scintillation proximity assay (SPA) as described in several references, such as N. D. Cook, et al., Pharmaceutical Manufacturing International, pages 49-53 (1992); K. Takeuchi, Laboratory Practice, September issue (1992); U.S. Pat. No. 4,568,649 (1986); which are incorporated by reference herein. Reactions are performed in 96-well plates. The assay is conducted in 100 xcexcl volume with 5.4 mM HEPE (pH 7.5), 11.7 mM KCl, 4.5 mM MgCl2, 0.36 mg/ml BSA, and 90 nM 3H-dTTP. Assays are run with and without CHAPS, (3-[(3-cholamidopropyl)-dimethylammonio]-1-propane-sulfonate) at a final concentration of 2 mM. HCMV polymerase is diluted in enzyme dilution buffer containing 50% glycerol, 250 mM NaCl, 10 mM HEPES (pH 7.5), 100 xcexcg/ml BSA, and 0.01% sodium azide. The HCMV polymerase, which is expressed in recombinant baculovirus-infected SF-9 cells and purified according to literature procedures, is added at 10% (or 10 xcexcl) of the final reaction volume, i.e., 100 xcexcl. Compounds are diluted in 50% DMSO and 10 xcexcl are added to each well. Control wells contain an equivalent concentration of DMSO. Unless noted otherwise, reactions are initiated via the addition of 6 nM biotinylated poly(dA)-oligo(dT) template/primer to reaction mixtures containing the enzyme, substrate, and compounds of interest. Plates are incubated in a 25 C or 37 C H2O bath and terminated via the addition of 40 xcexcl/reaction of 0.5 M EDTA (pH 8) per well. Reactions are terminated within the time-frame during which substrate incorporation is linear and varied depending upon the enzyme and conditions used, i.e., 30 min. for HCMV polymerase. Ten xcexcl of streptavidin-SPA beads (20 mg/ml in PBS/10% glycerol) are added following termination of the reaction. Plates are incubated 10 min. at 37 xc2x0 C., then equilibrated to room temperature, and counted on a Packard Topcount. Linear regressions are performed and IC50""s are calculated using computer software.
A modified version of the above HCMV polymerase assay is performed as described above, but with the following changes: Compounds are diluted in 100% DMSO until final dilution into assay buffer. In the previous assay, compounds are diluted in 50% DMSO. 4.5 mM dithiothreotol (DTT) is added to the polymerase buffer. Also, a different lot of CMV polymerase is used, which appears to be more active resulting in a more rapid polymerase reaction. Results of the testing of representative compounds of formula I in this assay are shown in Table 1. In Table 1, the term xe2x80x9cndxe2x80x9d refers to activity data not determined.